About half of the American military's supply of anthrax vaccine will be stockpiled for civilians in case of a bioterrorism attack.
Vaccination of US troops abroad remains the top priority, officials said.
Roughly half the millions of doses expected to be available eventually will be set aside for civilians, said William Winkenwerder, assistant secretary of defence for health affairs.
The vaccine will not be available for civilians to buy. And civilians will get the shots only if they are exposed to the deadly anthrax bacteria, said William Raub, an Health and Human Services deputy director for public health preparedness.
In contrast, the Pentagon programme vaccinates soldiers ahead of time as a precaution against possible exposure.
Exposed citizens - whether police, emergency workers or anyone - would get the vaccination along with antibiotics, a regime offered to postal workers and others exposed in last autumn's still unsolved anthrax mail attacks.
Those, along with the September 11 hijacked plane attacks on America, have prompted the new policy to split the drug between civilian and military communities, officials said.
For two years, the vaccine has been reserved for troops on special missions and for researchers. Starting immediately, the vaccine was to be given to a significantly greater number of troops, Mr Winkenwerder said.
PA